Circuit substrate material, circuits comprising the same, and method of manufacture thereof

Abstract

An electrical circuit material having a conductive layer disposed a substrate, wherein the substrate is formed from a thermosetting composition comprising a polybutadiene or polyisoprene resin; an optional, functionalized liquid polybutadiene or polyisoprene resin; an optional butadiene- or isoprene-containing copolymer; an optional low molecular weight polymer; an optional curing agent; a cross-linking agent; a particulate fluoropolymer; and about 20 to about 50 percent by weight, based on the total weight of the thermosetting composition, of a magnesium hydroxide having a low ionic content. Use of magnesium hydroxide allows the composition to attain a high level of flame retardancy without use of halogenated flame retardants, while maintaining good moisture absorption and other physical properties.

1 . A method of making an electrical circuit substrate material, the method comprising 
 disposing onto a conductive layer a thermosetting composition comprising    a polybutadiene or polyisoprene resin;    a cross-linking agent;    a particulate fluoropolymer; and    about 20 to about 50 percent by weight, based on the total weight of the thermosetting composition, of a magnesium hydroxide having less than about 1000 ppm of ionic contaminants; and    curing the thermosetting composition    wherein the substrate has a UL-94 rating of at least V-1.    
   
   
       2 . The method of  claim 1 , wherein the thermosetting composition further comprises a butadiene- or isoprene-containing copolymer.  
   
   
       3 . The method of  claim 2 , wherein the butadiene- or isoprene-containing copolymer is an unsaturated butadiene- or isoprene-containing copolymer.  
   
   
       4 . The method of  claim 3 , wherein the volume to volume ratio of the polybutadiene or polyisoprene resin to the unsaturated butadiene- or isoprene-containing copolymer is between 1:9 and 9:1, inclusive.  
   
   
       5 . The method of  claim 1 , wherein the thermosetting composition further comprises a curing agent.  
   
   
       6 . The method of  claim 5 , wherein the curing agent is an organic peroxide, a dicumyl peroxide, a di(2-tert-butylperoxyisopropyl) benzene, a t-butylperbenzoate, a t-butylperoxy hexyne-3, or a combination comprising one or more of the foregoing curing agents.  
   
   
       7 . The method of  claim 1 , wherein the thermosetting composition further comprises a low molecular weight polymer.  
   
   
       8 . The method of  claim 1 , wherein the thermosetting composition further comprises a functionalized liquid polybutadiene or polyisoprene resin.  
   
   
       9 . The method of  claim 1 , wherein the cross-linking agent is triallylisocyanurate, triallylcyanurate, diallyl phthalate, divinyl benzene, a multifunctional acrylate monomer, or a combination comprising one or more of the foregoing cross-linking agents.  
   
   
       10 . The method of  claim 1 , wherein the particulate fluoropolymer is a difluoroethylene polymer, a tetrafluoroethylene polymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a copolymer of tetrafluoroethylene with fluorine-free ethylenic monomers, or a combination comprising one or more of the foregoing particulate fluoropolymers.  
   
   
       11 . The method of  claim 1 , wherein the substrate has a moisture absorption value less than about 0.2% and a UL-94 flammability rating of V-0.  
   
   
       12 . The method of  claim 1 , wherein the substrate has a dielectric constant less than about 4.5 and a dielectric loss factor less than about 0.01.  
   
   
       13 . The method of  claim 1 , wherein the conductive layer is copper.  
   
   
       14 . The method of  claim 1 , wherein the thermosetting composition further comprises a woven or non-woven glass web.  
   
   
       15 . The electrical circuit material of  claim 1 , wherein the magnesium hydroxide comprises less than about 500 ppm of metal.  
   
   
       16 . The method of  claim 1 , wherein the thermosetting composition further comprises a chlorine-containing flame retardant, a bromine-containing flame retardant, or a combination comprising one or more of the foregoing flame retardants.  
   
   
       17 . The method of  claim 1 , wherein the magnesium hydroxide has an average surface area of about 3 to about 12 meters squared per gram.  
   
   
       18 . The method of  claim 1 , wherein the magnesium hydroxide is coated with an aminosilane.  
   
   
       19 . The method of  claim 1 , further comprising a filler.  
   
   
       20 . The method of  claim 19 , where the filler further comprises a coupling agent.  
   
   
       21 . The method of  claim 19 , where the coupling agent is a silane.